[libs][iOS] TimeZoneInfo StandardName/DisplayName display abbreviations instead of full name

[mdh1418]

Description

As mentioned in #85126 (comment), StandardName and DisplayName return abbreviations instead of the full name that other platforms return. This is likely due to iOS using its own version of ICU, and the data there not being complete enough to return the full name. As a result, it is likely that the backup values

runtime/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.cs

Line 244 in 764f774

string? standardDisplayName = _standardAbbrevName;

and

runtime/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.cs

Line 258 in 764f774

string? daylightDisplayName = _daylightAbbrevName ?? _standardAbbrevName;

are being used instead.

Reproduction Steps

Run the iOS sample src/mono/sample/iOS with

Console.WriteLine("StandardName: {TimeZoneInfo.Local.StandardName}");
Console.WriteLine("DaylightName: {TimeZoneInfo.Local.DaylightName}");

Expected behavior

Should see full names and not abbreviations, and since I'm based on East coast of North America,
Eastern Standard Time
Easter Daylight Time

Actual behavior

I'm based on East coast of North America, so
EST
EDT

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Tagging subscribers to this area: @dotnet/area-system-datetime
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

As mentioned in #85126 (comment), StandardName and DisplayName return abbreviations instead of the full name that other platforms return. This is likely due to iOS using its own version of ICU, and the data there not being complete enough to return the full name. As a result, it is likely that the backup values

runtime/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.cs

Line 244 in 764f774

string? standardDisplayName = _standardAbbrevName;

and

runtime/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.cs

Line 258 in 764f774

string? daylightDisplayName = _daylightAbbrevName ?? _standardAbbrevName;

are being used instead.

Reproduction Steps

Run the iOS sample src/mono/sample/iOS with

Console.WriteLine("StandardName: {TimeZoneInfo.Local.StandardName}");
Console.WriteLine("DaylightName: {TimeZoneInfo.Local.DaylightName}");

Expected behavior

Should see full names and not abbreviations, and since I'm based on East coast of North America,
Eastern Standard Time
Easter Daylight Time

Actual behavior

I'm based on East coast of North America, so
EST
EDT

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	mdh1418
Assignees:	-
Labels:	area-System.DateTime
Milestone:	-

Tagging subscribers to 'os-ios': @steveisok, @akoeplinger, @kotlarmilos
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

As mentioned in #85126 (comment), StandardName and DisplayName return abbreviations instead of the full name that other platforms return. This is likely due to iOS using its own version of ICU, and the data there not being complete enough to return the full name. As a result, it is likely that the backup values

runtime/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.cs

Line 244 in 764f774

string? standardDisplayName = _standardAbbrevName;

and

runtime/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.cs

Line 258 in 764f774

string? daylightDisplayName = _daylightAbbrevName ?? _standardAbbrevName;

are being used instead.

Reproduction Steps

Run the iOS sample src/mono/sample/iOS with

Console.WriteLine("StandardName: {TimeZoneInfo.Local.StandardName}");
Console.WriteLine("DaylightName: {TimeZoneInfo.Local.DaylightName}");

Expected behavior

Should see full names and not abbreviations, and since I'm based on East coast of North America,
Eastern Standard Time
Easter Daylight Time

Actual behavior

I'm based on East coast of North America, so
EST
EDT

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	mdh1418
Assignees:	-
Labels:	untriaged, os-ios, area-System.DateTime
Milestone:	-

[tarekgh]

@steveisok could you please triage as it is iOS?

[steveisok]

I think this is something we can tweak in the ICU filter for iOS.

[mdh1418]

After Meri's work in #91458, the DisplayName/StandardName/DaylightName TimeZoneInfo properties are no longer abbreviations when HybridGlobalization is enabled. When HybridGlobalization is not enabled, default values (abbreviated form) will be used similar to Invariant globalization mode.